This is my first post on this forum. I am really glad to have found it, as I've been recently diagnosed with low B12, but my own research has been more valuable than my doctors' knowledge on the subject.

My level tested in February was 204. The doctor who found this gave me a shot of B12 and I felt better almost immediately. He said that I'd get another one in a month, and that if I wanted to in the meantime I could take B12 supplements or didn't have to (see what I mean about doctor's lack of knowledge?).
A few days after the shot I tried a 3000mcg sublingual B12 pill and it drove me crazy. I immediately called the doctor office and they said that if I'm getting the shots once a month I don't need the pills. I immediately stopped the pills.

Nearly a month went by and I started to feel very sick. I would get very weak, confused, fatigued, feel like the life was just sucked out of me. I began to have spots in my vision and felt like I was going to pass out and die.
I called the doctor office a couple days early to request the shot as I think I was experiencing symptoms of low B12. They gave me the shot and that evening I felt better again. This lasted all of two days and I felt just as sick as I did that day I called their office. I went back to talk to the doctor who said you only need it every month and the levels should go up. I knew then and there I'd have to go to a different doctor to get more B12.

I called my primary care physician with tears in my eyes (because I was so weak and sick I thought I was going to die, literally) and went into his office and begged for more B12 injections. By the way, I had tried another sublingual tablet prior to this office visit and again had a terrible negative reaction. It just made me feel crazy and sick.
My therapist said it was likely the sugar additive ingredients that did this, this one in particular was xylitol. She said she's seen it make others sick before, and many just can't tolerate them.

My primary care obliged and gave me intramuscular shots that I could give myself. He gave me cyanocobalamin, and I seemed to do OK. I took it more often than he prescribed based on a treatment protocol I found online. I went back to his office and requested methylcobalamin shots and that I could have them every-other-day for two weeks, then maybe once a week for a month then re-assess.

I haven't taken any shots in a couple days, and I already feel out of it. Confused, in pain (not sure if this pain is specifically from this, but I am wondering if it is...), fatigued, feel sick like I may pass out. In any event, I will give myself the last of the two-week every-other-daily dosings tomorrow morning of 1000mcg IM methylcobalamin.

My question is in regards to daily oral dosings. I am reading on this thread and another website (the Rose's website) that one can take 1000-2000 or more (up to about 5000) mcg of oral cobalamin (in either cayno or methyl, or others) every day and have just as good results, because regarless of the fact that if you have intrinsic factor or not, you will scrape just enough from a mega dose to get enough you need (1-10% of the pill).

My question is this - given I cannot tolerate sublinguals (and is this heard of? does anyone else not have the ability to tolerate sublinguals for some reason?), would I be OK to try an oral dose, one that is not sublingual but is rather swallowed, and later absorbed by the intestine? I do not know if I am missing intrinsic factor or not. That was my reason behind trying sublinguals. However, I found that for whatever reason I just cannot tolerate them.

I am so confused and disturbed by this. I do not know why my levels are low or where this came from and for how long I've had it. I have a range of strange things going on with my body, and I'm not sure how much is attributed to low B12 or is from other factors (recently stopped almost 10 years of antidepressant use, had some horrific adverse reactions to one of them, was on a mega dose of another that I shouldn't have been on, etc.).

I have a lot of strange pain and cracking in my upper back and joints, almost like fibro like pains up there. I have a lot of cognitive difficulties (forgetting things, feeling detached from reality, having a hard time focusing and learning new things), and I had many classic low b12 signs like pallor, heavy breathing, confusion, dizziness, low appetite, bleeding gums, greying of hairs (I'm 30!)and other things.

Any advice anyone could give me would be greatly appreciated. I am so glad I ran across these threads.

J